Power management for distributed communication systems, and related components, systems, and methods

ABSTRACT

Power management techniques in distributed communication systems in which the power available at a remote unit (RU) is measured and compared to the power requirements of the RU. Voltage and current are measured for two dummy loads at the RU and these values are used to solve for the output voltage of the power supply and the resistance of the wires. From these values, a maximum power available may be calculated and compared to power requirements of the RU.

RELATED APPLICATION

This application is a continuation of International Application No. PCT/IL14/050766 filed on Aug. 26, 2014 which claims the benefit of priority to U.S. Provisional Application No. 61/870,976, filed on Aug. 28, 2013, both applications being incorporated herein by reference.

The present application is related to U.S. patent application Ser. No. 13/687,457, filed Nov. 28, 2012, entitled “Power Management For Distributed Communication Systems, and Related Components, Systems, and Methods,” published as U.S. Pub. No. 20140146692 A1, which is incorporated herein by reference in its entirety.

BACKGROUND

The technology of the disclosure relates to managing power in remote units in a distributed communication system.

Wireless communication is rapidly growing, with ever-increasing demands for high-speed mobile data communication. As an example, so-called “wireless fidelity” or “WiFi” systems and wireless local area networks (WLANs) are being deployed in many different types of areas (e.g., coffee shops, airports, libraries, etc.). Distributed communications or distributed antenna systems communicate with wireless devices called “clients,” which must reside within the wireless range or “cell coverage area” to communicate with an access point device.

One approach to deploying a distributed antenna system involves the use of radio frequency (RF) antenna coverage areas, also referred to as “antenna coverage areas.” Antenna coverage areas can have a radius in the range from a few meters up to twenty meters as an example. Combining a number of access point devices creates an array of antenna coverage areas. Because the antenna coverage areas each cover small areas, there are typically only a few users (clients) per antenna coverage area. This allows for minimizing the amount of RF bandwidth shared among the wireless system users. It may be desirable to provide antenna coverage areas in a building or other facility to provide distributed antenna system access to clients within the building or facility. However, it may be desirable to employ optical fiber to distribute communication signals. Benefits of optical fiber include increased bandwidth.

One type of distributed antenna system for creating antenna coverage areas includes distribution of RF communications signals over an electrical conductor medium, such as coaxial cable or twisted pair wiring. Another type of distributed antenna system for creating antenna coverage areas, called “Radio-over-Fiber” or “RoF,” utilizes RF communications signals sent over optical fibers. Both types of systems can include head-end equipment coupled to a plurality of remote units (RUs), which may include an antenna and may be referred to as a remote antenna unit or RAU. Each RU provides antenna coverage areas. The RUs can each include RF transceivers coupled to an antenna to transmit RF communications signals wirelessly, wherein the RUs are coupled to the head-end equipment via the communication medium. The RF transceivers in the RUs are transparent to the RF communications signals. The antennas in the RUs also receive RF signals (i.e., electromagnetic radiation) from clients in the antenna coverage area. The RF signals are then sent over the communication medium to the head-end equipment. In optical fiber or RoF distributed antenna systems, the RUs convert incoming optical RF signals from an optical fiber downlink to electrical RF signals via optical-to-electrical (O/E) converters, which are then passed to the RF transceiver. The RUs also convert received electrical RF communications signals from clients via the antennas to optical RF communications signals via electrical-to-optical (E/O) converters. The optical RF signals are then sent over an optical fiber uplink to the head-end equipment.

The RUs contain power-consuming components, such as the RF transceiver, to transmit and receive RF communications signals and thus require power to operate. In the situation of an optical fiber-based distributed antenna system, the RUs may contain 0/E and E/O converters that also require power to operate. In some installations, the RU may contain a housing that includes a power supply to provide power to the RUs locally at the RU. The power supply may be configured to be connected to a power source, such as an alternating current (AC) power source, and convert AC power into a direct current (DC) power signal. Alternatively, power may be provided to the RUs from remote power supplies. The remote power supplies may be configured to provide power to multiple RUs. It may be desirable to provide these power supplies in modular units or devices that may be easily inserted or removed from a housing to provide power. Providing modular power distribution modules allows power to more easily be configured as needed for the distributed antenna system. For example, a remotely located power unit may be provided that contains a plurality of ports or slots to allow a plurality of power distribution modules to be inserted therein. The power unit may have ports that allow the power to be provided over an electrical conductor medium to the RUs. Thus, when a power distribution module is inserted into the power unit in a port or slot that corresponds to a given RU, power from the power distribution module is supplied to the RU.

RUs may also provide wired communication ports or provide other services, each of which may require power consumption at the RU. The cumulative effect of all the power consuming components at the RUs may exceed the power provided from the remote power supply. When the power requirements exceed the available power, the RU may shut down and provide no services or may have other disturbances in the operation of the RU.

Even when the remote power source is initially adequate to supply sufficient power to the RUs, some of the power is lost on the wires carrying the power. Additionally, some power supplies may be set to the wrong power setting or have other malfunctions. When an RU is designed to consume power at close to the maximum power available from the remote power supply, it becomes important to verify that the expected power is actually available at the ports of the RU. As noted above, if the power available at the ports is below what is required, the RU may shut down and provide no services, or may have other disturbances in the operation of the RU.

No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents.

SUMMARY OF THE DETAILED DESCRIPTION

Embodiments disclosed in the detailed description include power management techniques in distributed communication systems. Related components, systems, and methods are also disclosed. In embodiments disclosed herein, the power available at a remote unit (RU) is measured and compared to the power requirements of the RU. In an exemplary embodiment, voltage and current is measured for two dummy loads at the RU and these values are used to solve for the output voltage of the power supply and the resistance of the wires. From these values, a maximum power available may be calculated and compared to power requirements of the RU.

One embodiment of the disclosure relates to a RU for use in a distributed communication system. The RU is comprised of at least one antenna configured to transmit radio frequency signals into a coverage area. The RU is also comprised of a power unit configured to receive a power signal from a power distribution module through a power medium, a power over Ethernet integrated circuit (POE IC) configured to measure voltage and current from the power input, and a control system. The control system is configured to open a services switch between the power input and a real load, to instruct the POE IC to close a first switch coupling a first load resistance to the power input, to instruct the POE IC to measure a first voltage and a first current associated with the first load resistance, and to instruct the POE IC to open the first switch and close a second switch coupling a second load resistance to the power input. The control system is also configured to instruct the POE IC to measure a second voltage and a second current associated with the second load resistance and to calculate an available power for the RU. The remote unit includes at least one antenna unit for at least one of transmitting signals into and receiving signals from a coverage area.

An additional embodiment of the disclosure relates to a method of managing power in a RU of a distributed communication system. The method comprises opening a services switch associated with a real load and while a first switch associated with a first resistance is closed, measuring a first voltage and first current associated with the first resistance, and while a second switch associated with a second resistance is closed, measuring a second voltage and a second current associated with the second resistance. The method also comprises calculating an available power for the RU based on the first current, the first voltage, the second current and the second voltage.

An additional embodiment of the disclosure relates to a distributed communication system. The distributed communication system comprises a plurality of remote units. Each remote unit comprises at least one antenna configured to transmit radio frequency signals into a coverage area. Each RU is also comprised of a power unit configured to receive a power signal from a power distribution module through a power medium, a power over Ethernet integrated circuit (POE IC) configured to measure voltage and current from the power input, and a control system. The control system is configured to open a services switch between the power input and a real load, to instruct the POE IC to close a first switch coupling a first load resistance to the power input, to instruct the POE IC to measure a first voltage and a first current associated with the first load resistance, and to instruct the POE IC to open the first switch and close a second switch coupling a second load resistance to the power input. The control system is also configured to instruct the POE IC to measure a second voltage and a second current associated with the second load resistance and to calculate an available power for the RU.

Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments as described in the written description and the claims hereof, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following detailed description are merely embodiments, and are intended to provide an overview or framework to understand the nature and character of the claims.

The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description, serve to explain principles and operation of the various embodiments.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram of an exemplary distributed antenna system;

FIG. 2A is a partially schematic cut-away diagram of an exemplary building infrastructure in which the distributed antenna system in FIG. 1 can be employed;

FIG. 2B is an alternative diagram of the distributed antenna system in FIG. 2A;

FIG. 3 is a schematic diagram of providing digital data services and radio frequency (RF) communication services to remote units (RUs) or other remote communications devices in the distributed antenna system of FIG. 1;

FIG. 4 is a schematic diagram of an exemplary power distribution module that is supported by an exemplary power unit;

FIG. 5 is a schematic diagram of an exemplary power management module according to an exemplary embodiment of the present disclosure;

FIG. 6 is a flow chart of an exemplary process used by a power management module according to FIG. 5; and

FIG. 7 is a schematic diagram of a generalized representation of an exemplary computer system that can be used for controlling the power distribution modules disclosed herein, wherein the exemplary computer system is adapted to execute instructions from an exemplary computer-readable media.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all embodiments are shown. Indeed, the concepts may be embodied in many different forms and should not be construed as limiting herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts. Various embodiments will be further clarified by the following examples.

Embodiments disclosed in the detailed description include power management techniques in distributed communication systems. Related components, systems, and methods are also disclosed. In embodiments disclosed herein, the power available at a remote unit (RU) is measured and compared to the power requirements of the RU. In an exemplary embodiment, voltage and current is measured for two dummy loads at the RU and these values are used to solve for the output voltage of the power supply and the resistance of the wires. From these values, a maximum power available may be calculated and compared to power requirements of the RU.

While the concepts of the present disclosure are applicable to different types of distributed communication systems, an exemplary embodiment is used in a distributed antenna system and this exemplary embodiment is explored herein. Before discussing an exemplary power management system, exemplary distributed antenna systems capable of distributing radio frequency (RF) communications signals to distributed or remote units (RUs) are first described with regard to FIGS. 1-3. It should be appreciated that in an exemplary embodiment the RUs may contain antennas such that the RU is a remote antenna unit and may be referred to as a RAU.

In this regard, the distributed antenna systems in FIGS. 1-3 can include power units located remotely from RUs that provide power to the RUs for operation. Embodiments of power management modules in a distributed communication system, including the distributed antenna systems in FIGS. 1-3, begin with FIG. 4. The distributed antenna systems in FIGS. 1-3 discussed below include distribution of RF communications signals; however, the distributed antenna systems are not limited to distribution of RF communications signals. Also note that while the distributed antenna systems in FIGS. 1-3 discussed below include distribution of communications signals over optical fiber, these distributed antenna systems are not limited to distribution over optical fiber. Distribution mediums could also include, but are not limited to, coaxial cable, twisted-pair conductors, wireless transmission and reception, and any combination thereof. Also, any combination can be employed that also involves optical fiber for portions of the distributed antenna system.

In this regard, FIG. 1 is a schematic diagram of an embodiment of a distributed antenna system. In this embodiment, the system is an optical fiber-based distributed antenna system 10. The distributed antenna system 10 is configured to create one or more antenna coverage areas for establishing communications with wireless client devices located in the RF range of the antenna coverage areas. The distributed antenna system 10 provides RF communication services (e.g., cellular services). In this embodiment, the distributed antenna system 10 includes head-end equipment (HEE) 12 such as a head-end unit (HEU), one or more RUs 14, and an optical fiber 16 that optically couples the HEE 12 to the RU 14. The RU 14 is a type of remote communications unit. In general, a remote communications unit can support wireless communications, wired communications, or both. The RU 14 can support wireless communications and may also support wired communications through wired service port 40. The HEE 12 is configured to receive communications over downlink electrical RF signals 18D from a source or sources, such as a network or carrier as examples, and provide such communications to the RU 14. The HEE 12 is also configured to return communications received from the RU 14, via uplink electrical RF signals 18U, back to the source or sources. In this regard in this embodiment, the optical fiber 16 includes at least one downlink optical fiber 16D to carry signals communicated from the HEE 12 to the RU 14 and at least one uplink optical fiber 16U to carry signals communicated from the RU 14 back to the HEE 12.

One downlink optical fiber 16D and one uplink optical fiber 16U could be provided to support multiple channels each using wave-division multiplexing (WDM), as discussed in U.S. patent application Ser. No. 12/892,424 entitled “Providing Digital Data Services in Optical Fiber-based Distributed Radio Frequency (RF) Communications Systems, And Related Components and Methods,” incorporated herein by reference in its entirety. Other options for WDM and frequency-division multiplexing (FDM) are disclosed in U.S. patent application Ser. No. 12/892,424, any of which can be employed in any of the embodiments disclosed herein. Further, U.S. patent application Ser. No. 12/892,424 also discloses distributed digital data communications signals in a distributed antenna system which may also be distributed in the optical fiber-based distributed antenna system 10 either in conjunction with RF communications signals or not.

The optical fiber-based distributed antenna system 10 has an antenna coverage area 20 that can be disposed about the RU 14. The antenna coverage area 20 of the RU 14 forms an RF coverage area 38. The HEE 12 is adapted to perform or to facilitate any one of a number of Radio-over-Fiber (RoF) applications, such as RF identification (RFID), wireless local-area network (WLAN) communication, or cellular phone service. Shown within the antenna coverage area 20 is a client device 24 in the form of a mobile device as an example, which may be a cellular telephone as an example. The client device 24 can be any device that is capable of receiving RF communications signals. The client device 24 includes an antenna 26 (e.g., a wireless card) adapted to receive and/or send electromagnetic RF signals.

With continuing reference to FIG. 1, to communicate the electrical RF signals over the downlink optical fiber 16D to the RU 14, to in turn be communicated to the client device 24 in the antenna coverage area 20 formed by the RU 14, the HEE 12 includes a radio interface in the form of an electrical-to-optical (E/O) converter 28. The E/O converter 28 converts the downlink electrical RF signals 18D to downlink optical RF signals 22D to be communicated over the downlink optical fiber 16D. The RU 14 includes an optical-to-electrical (O/E) converter 30 to convert received downlink optical RF signals 22D back to electrical RF signals to be communicated wirelessly through an antenna 32 of the RU 14 to client devices 24 located in the antenna coverage area 20.

Similarly, the antenna 32 is also configured to receive wireless RF communications from client devices 24 in the antenna coverage area 20. In this regard, the antenna 32 receives wireless RF communications from client devices 24 and communicates electrical RF signals representing the wireless RF communications to an E/O converter 34 in the RU 14. The E/O converter 34 converts the electrical RF signals into uplink optical RF signals 22U to be communicated over the uplink optical fiber 16U. An O/E converter 36 provided in the HEE 12 converts the uplink optical RF signals 22U into uplink electrical RF signals, which can then be communicated as uplink electrical RF signals 18U back to a network or other source.

To provide further exemplary illustration of how a distributed antenna system can be deployed indoors, FIG. 2A is provided. FIG. 2A is a partially schematic cut-away diagram of a building infrastructure 50 employing an optical fiber-based distributed antenna system. The system may be the optical fiber-based distributed antenna system 10 of FIG. 1. The building infrastructure 50 generally represents any type of building in which the optical fiber-based distributed antenna system 10 can be deployed. As previously discussed with regard to FIG. 1, the optical fiber-based distributed antenna system 10 incorporates the HEE 12 to provide various types of communication services to coverage areas within the building infrastructure 50, as an example.

For example, as discussed in more detail below, the distributed antenna system 10 in this embodiment is configured to receive wireless RF signals and convert the RF signals into RoF signals to be communicated over the optical fiber 16 to multiple RUs 14. The optical fiber-based distributed antenna system 10 in this embodiment can be, for example, an indoor distributed antenna system (IDAS) to provide wireless service inside the building infrastructure 50. These wireless signals can include cellular service, wireless services such as RFID tracking, Wireless Fidelity (WiFi), local area network (LAN), WLAN, public safety, wireless building automations, and combinations thereof, as examples.

With continuing reference to FIG. 2A, the building infrastructure 50 in this embodiment includes a first (ground) floor 52, a second floor 54, and a third floor 56. The floors 52, 54, 56 are serviced by the HEE 12 through a main distribution frame 58 to provide antenna coverage areas 60 in the building infrastructure 50. Only the ceilings of the floors 52, 54, 56 are shown in FIG. 2A for simplicity of illustration. In the example embodiment, a main cable 62 has a number of different sections that facilitate the placement of a large number of RUs 14 in the building infrastructure 50. Each RU 14 in turn services its own coverage area in the antenna coverage areas 60. The main cable 62 can include, for example, a riser cable 64 that carries all of the downlink and uplink optical fibers 16D, 16U to and from the HEE 12. The riser cable 64 may be routed through a power unit 70. The power unit 70 may also be configured to provide power to the RUs 14 via an electrical power line provided inside an array cable 72, or tail cable or home-run tether cable as other examples, and distributed with the downlink and uplink optical fibers 16D, 16U to the RUs 14. For example, as illustrated in the building infrastructure 50 in FIG. 2B, a tail cable 80 may extend from the power units 70 into an array cable 82. Downlink and uplink optical fibers in tether cables 84 of the array cables 82 are routed to each of the RUs 14, as illustrated in FIG. 2B. Referring back to FIG. 2A, the main cable 62 can include one or more multi-cable (MC) connectors adapted to connect select downlink and uplink optical fibers 16D, 16U, along with an electrical power line, to a number of optical fiber cables 66.

With continued reference to FIG. 2A, the main cable 62 enables multiple optical fiber cables 66 to be distributed throughout the building infrastructure 50 (e.g., fixed to the ceilings or other support surfaces of each floor 52, 54, 56) to provide the antenna coverage areas 60 for the first, second, and third floors 52, 54, and 56. In an example embodiment, the HEE 12 is located within the building infrastructure 50 (e.g., in a closet or control room), while in another example embodiment, the HEE 12 may be located outside of the building infrastructure 50 at a remote location. A base transceiver station (BTS) 68, which may be provided by a second party such as a cellular service provider, is connected to the HEE 12, and can be co-located or located remotely from the HEE 12. A BTS (such as BTS 68) is any station or signal source that provides an input signal to the HEE 12 and can receive a return signal from the HEE 12.

In a typical cellular system, for example, a plurality of BTSs is deployed at a plurality of remote locations to provide wireless telephone coverage. Each BTS serves a corresponding cell and when a mobile client device enters the cell, the BTS communicates with the mobile client device. Each BTS can include at least one radio transceiver for enabling communication with one or more subscriber units operating within the associated cell. As another example, wireless repeaters or bi-directional amplifiers could also be used to serve a corresponding cell in lieu of a BTS. Alternatively, radio input could be provided by a repeater, picocell, or femtocell as other examples.

The optical fiber-based distributed antenna system 10 in FIGS. 1-2B and described above provides point-to-point communications between the HEE 12 and the RU 14. A multi-point architecture is also possible as well. With regard to FIGS. 1-2B, each RU 14 communicates with the HEE 12 over a distinct downlink and uplink optical fiber pair to provide the point-to-point communications. Whenever an RU 14 is installed in the optical fiber-based distributed antenna system 10, the RU 14 is connected to a distinct downlink and uplink optical fiber pair connected to the HEE 12. The downlink and uplink optical fibers 16D, 16U may be provided in a fiber optic cable. Multiple downlink and uplink optical fiber pairs can be provided in a fiber optic cable to service multiple RUs 14 from a common fiber optic cable.

For example, with reference to FIG. 2A, RUs 14 installed on a given floor 52, 54, or 56 may be serviced from the same optical fiber 16. In this regard, the optical fiber 16 may have multiple nodes where distinct downlink and uplink optical fiber pairs can be connected to a given RU 14.

The HEE 12 may be configured to support any frequencies desired, including but not limited to US FCC and Industry Canada frequencies (824-849 MHz on uplink and 869-894 MHz on downlink), US FCC and Industry Canada frequencies (1850-1915 MHz on uplink and 1930-1995 MHz on downlink), US FCC and Industry Canada frequencies (1710-1755 MHz on uplink and 2110-2155 MHz on downlink), US FCC frequencies (698-716 MHz and 776-787 MHz on uplink and 728-746 MHz on downlink), EU R & TTE frequencies (880-915 MHz on uplink and 925-960 MHz on downlink), EU R & TTE frequencies (1710-1785 MHz on uplink and 1805-1880 MHz on downlink), EU R & TTE frequencies (1920-1980 MHz on uplink and 2110-2170 MHz on downlink), US FCC frequencies (806-824 MHz on uplink and 851-869 MHz on downlink), US FCC frequencies (896-901 MHz on uplink and 929-941 MHz on downlink), US FCC frequencies (793-805 MHz on uplink and 763-775 MHz on downlink), and US FCC frequencies (2495-2690 MHz on uplink and downlink).

FIG. 3 is a schematic diagram of another exemplary optical fiber-based distributed antenna system 90 that may be employed according to the embodiments disclosed herein to provide RF communication services. In this embodiment, the optical fiber-based distributed antenna system 90 includes optical fiber for distributing RF communication services. The optical fiber-based distributed antenna system 90 in this embodiment is comprised of three (3) main components. One or more radio interfaces provided in the form of radio interface modules (RIMs) 92(1)-92(M) in this embodiment are provided in HEE 94 to receive and process downlink electrical RF communications signals prior to optical conversion into downlink optical RF communications signals. The RIMs 92(1)-92(M) provide both downlink and uplink interfaces. The processing of the downlink electrical RF communications signals can include any of the processing previously described above in the HEE 12 in FIGS. 1-2A. The notation “1-M” indicates that any number of the referenced component, 1-M may be provided. The HEE 94 is configured to accept a plurality of RIMs 92(1)-92(M) as modular components that can easily be installed and removed or replaced in the HEE 94. In one embodiment, the HEE 94 is configured to support up to eight (8) RIMs 92(1)-92(M).

With continuing reference to FIG. 3, each RIM 92(1)-92(M) can be designed to support a particular type of radio source or range of radio sources (i.e., frequencies) to provide flexibility in configuring the HEE 94 and the optical fiber-based distributed antenna system 90 to support the desired radio sources. For example, one RIM 92 may be configured to support the Personal Communication Services (PCS) radio band. Another RIM 92 may be configured to support the 700 MHz radio band. In this example, by inclusion of these RIMs 92, the HEE 94 would be configured to support and distribute RF communications signals on both PCS and LTE 700 radio bands. RIMs 92 may be provided in the HEE 94 that support any frequency bands desired, including but not limited to the US Cellular band, PCS band, Advanced Wireless Services (AWS) band, 700 MHz band, Global System for Mobile communications (GSM) 900, GSM 1800, and Universal Mobile Telecommunication System (UMTS). RIMs 92 may be provided in the HEE 94 that support any wireless technologies desired, including but not limited to Code Division Multiple Access (CDMA), CDMA200, 1xRTT, Evolution-Data Only (EV-DO), UMTS, High-speed Packet Access (HSPA), GSM, General Packet Radio Services (GPRS), Enhanced Data GSM Environment (EDGE), Time Division Multiple Access (TDMA), Long Term Evolution (LTE), iDEN, and Cellular Digital Packet Data (CDPD). RIMs 92 may be provided in the HEE 94 that support any frequencies desired referenced above as non-limiting examples.

With continuing reference to FIG. 3, the downlink electrical RF communications signals are provided to a plurality of optical interfaces provided in the form of optical interface modules (OIMs) 96(1)-96(N) in this embodiment to convert the downlink electrical RF communications signals into downlink optical RF communications signals 100D. The notation “1-N” indicates that any number of the referenced component 1-N may be provided. The OIMs 96 may be configured to provide one or more optical interface components (OICs) that contain O/E and E/O converters, as will be described in more detail below. The OIMs 96 support the radio bands that can be provided by the RIMs 92, including the examples previously described above. Thus, in this embodiment, the OIMs 96 may support a radio band range from 400 MHz to 2700 MHz, as an example, so providing different types or models of OIMs 96 for narrower radio bands to support possibilities for different radio band-supported RIMs 92 provided in the HEE 94 is not required. Further, the OIMs 96 may be optimized for sub-bands within the 400 MHz to 2700 MHz frequency range, such as 400-700 MHz, 700 MHz-1 GHz, 1 GHz-1.6 GHz, and 1.6 GHz-2.7 GHz, as examples.

The OIMs 96(1)-96(N) each include E/O converters to convert the downlink electrical RF communications signals to downlink optical RF communications signals 100D. The downlink optical RF communications signals 100D are communicated over downlink optical fiber(s) to a plurality of RUs 102(1)-102(P). The notation “1-P” indicates that any number of the referenced component 1-P may be provided. O/E converters provided in the RUs 102(1)-102(P) convert the downlink optical RF communications signals 100D back into downlink electrical RF communications signals, which are provided over downlinks coupled to antennas 104(1)-104(P) in the RUs 102(1)-102(P) to client devices 24 (shown in FIG. 1) in the reception range of the antennas 104(1)-104(P).

E/O converters are also provided in the RUs 102(1)-102(P) to convert uplink electrical RF communications signals received from client devices through the antennas 104(1)-104(P) into uplink optical RF communications signals 100U to be communicated over uplink optical fibers to the OIMs 96(1)-96(N). The OIMs 96(1)-96(N) include O/E converters that convert the uplink optical RF communications signals 100U into uplink electrical RF communications signals that are processed by the RIMs 92(1)-92(M) and provided as uplink electrical RF communications signals. Downlink electrical digital signals 108D(1)-108D(P) communicated over downlink electrical medium or media (hereinafter “medium”) 110D are provided to the RUs 102(1)-102(P), separately from the RF communication services, as well as uplink electrical digital signals 108U(1)-108U(P) communicated over uplink electrical medium 110U, as also illustrated in FIG. 3. Power may be provided in the downlink and/or uplink electrical medium 110D and/or 110U to the RUs 102(1)-102(P).

In one embodiment, up to thirty-six (36) RUs 102 can be supported by the OIMs 96, three RUs 102 per OIM 96 in the optical fiber-based distributed antenna system 90 in FIG. 3. The optical fiber-based distributed antenna system 90 is scalable to address larger deployments. In the illustrated optical fiber-based distributed antenna system 90, the HEE 94 is configured to support up to thirty six (36) RUs 102 and fit in 6U rack space (U unit meaning 1.75 inches of height). The downlink operational input power level can be in the range of −15 dBm to 33 dBm. The adjustable uplink system gain range can be in the range of +15 dB to −15 dB. The RF input interface in the RIMs 92 can be duplexed and simplex, N-Type. The optical fiber-based distributed antenna system can include sectorization switches to be configurable for sectorization capability, as discussed in U.S. patent application Ser. No. 12/914,585 filed on Oct. 28, 2010, and entitled “Sectorization In Distributed Antenna Systems, and Related Components and Method,” which is incorporated herein by reference in its entirety.

In another embodiment, an exemplary RU 102 may be configured to support up to four (4) different radio bands/carriers (e.g. ATT, VZW, TMobile, Metro PCS: 700LTE/850/1900/2100). Radio band upgrades can be supported by adding remote expansion units over the same optical fiber (or upgrade to MIMO on any single band). The RUs 102 and/or remote expansion units may be configured to provide external filter interface to mitigate potential strong interference at 700MHz band (Public Safety, CH51,56); Single Antenna Port (N-type) provides DL output power per band (Low bands (<1 GHz): 14 dBm, High bands (>1 GHz): 15 dBm); and satisfies the UL System RF spec (UL Noise Figure: 12 dB, UL IIP3: -5 dBm, UL AGC: 25 dB range).

As further illustrated in FIG. 3, a power supply module (PSM) 118 may provide power to the RIMs 92(1)-92(M) and radio distribution cards (RDCs) 112 that distribute the RF communications from the RIMs 92(1)-92(M) to the OIMs 96(1)-96(N) through RDCs 114. In one embodiment, the RDCs 112, 114 can support different sectorization needs. A PSM 120 may also be provided to provide power to the OIMs 96(1)-96(N). An interface 116, which may include web and network management system (NMS) interfaces, may also be provided to allow configuration and communication to the RIMs 92(1)-92(M) and other components of the optical fiber-based distributed antenna system 90. A microcontroller, microprocessor, or other control circuitry, called a head-end controller (HEC) 122 may be included in HEE 94 to provide control operations for the HEE 94.

RUs, including the RUs 14, 102 discussed above, contain power-consuming components for transmitting and receiving RF communications signals. In the situation of an optical fiber-based distributed antenna system, the RUs 14, 102 may contain O/E and E/O converters that also require power to operate. As an example, a RU 14, 102 may contain a power unit that includes a power supply to provide power to the RUs 14, 102 locally at the RU 14, 102. Alternatively, power may be provided to the RUs 14, 102 from power supplies provided in remote power units such as power units 70. In either scenario, it may be desirable to provide these power supplies in modular units or devices that may be easily inserted or removed from a power unit. Providing modular power distribution modules allows power to more easily be configured as needed for the distributed antenna system.

In this regard, FIG. 4 is a schematic diagram of an exemplary power distribution module 130 that can be employed to provide power to the RUs 14, 102 or other power-consuming DAS components, including those described above. In this embodiment, the power distribution module 130 may be the power unit 70 previously described above to remotely provide power to the RUs 14, 102. The power unit 70 may be comprised of a chassis or other housing that is configured to support power distribution modules 130. The power distribution module 130 may include a power supply unit 132 that has a plurality of outputs 134, 136. The output 134 may be connected to a port 138. In an exemplary embodiment, the port 138 is a multi-connector port configured to accommodate a conventional plug such as a CAT 5 or CAT 6 plug and includes conductive elements configured to carry power.

The output 136 may have a reduced voltage relative to output 134 (e.g., 12 V compared to 56 V) and be coupled to a fan 140 with associated fan monitor 142 and fan alarm 144. The port 138 may further include conductive elements 146 configured to carry return signals from the RU 14, 102. While FIG. 4 illustrates an exemplary power distribution module 130, it should be appreciated that other power supply configurations may be used with embodiments of the present disclosure.

The power distribution module 130 provides power to the RU 102 through the electrical medium 110 as shown in FIG. 3 or 5. As illustrated in FIG. 5, the electrical medium 110 has a resistance R_(LINE) 149 which dissipates power thereby reducing the power that is available at the RU 102. The present disclosure provides, in exemplary embodiments, systems and techniques through which the power available at the RU 102 may be calculated and appropriate remedial action (if any) taken. In particular, in an exemplary embodiment, an alarm may be generated so that correction may be made. One such alarm may be a local light being illuminated. An alternate alarm may be a report via a management or telemetry channel to a central management system. In another exemplary embodiment, the RU 102 may prioritize services provided by the RU 102 and shut down lower priority services to prevent the other services supported by RU 102 from shutting down or having other anomalous and undesired operational behavior. In still another alternate and non-exclusive embodiment, the resistance value of R_(LINE) 149 may be reported to a central facility for future planning purposes. That is, the system operators may review the R_(LINE) 149 value when evaluating whether a potential upgrade is feasible at a particular RU 102. For example, if R_(LINE) 149 is high and there are already several services at a particular RU 102, then it may not be practical to add a service to that RU 102 unless an additional power source is provided. Still other planning decisions can be made as desired.

In this regard, the RU 102 includes a controller 150 and a power over Ethernet integrated circuit (POE IC) 152. In an exemplary embodiment, the POE IC may be the LTC4266IUHF#PBF sold by Linear Technology of 1630 McCarthy Blvd. Milpitas, Calif. 95035-7417. At the time of writing, the specification for this part was available at www.linear.com/product/LTC4266 and the datasheet was available at cds.linear.com/docs/en/datasheet/4266fd.pdf. The datasheet is herein incorporated by reference in its entirety. Other POE IC may also be used.

With continued reference to FIG. 5, the RU 102 includes a “real” load 154 selectively coupled to incoming power via switch 156. Switch 156 is sometimes referred to herein as a services switch. The “real” load 154 may include the O/E and E/O converters, RF transceivers, processors, and other elements that provide the primary services and functionality of the RU 102. The services may include cellular services such as those enumerated above, radio frequency communication services, WiFi, Ethernet, location based services, and the like. The services may be embodied in separate modules, separate circuit boards, antennas, or the like. As these services are conventional, further explanation of them is omitted. The switch 156 is operatively controlled by the controller 150.

With continued reference to FIG. 5, POE IC 152 includes a current sensor and a voltage sensor. When it is desired to calculate the available power at the RU 102, and specifically Pin at ports 158, 160, the controller 150 disconnects the “real” load 154 by opening switch 156 and instructs the POE IC 152 to close switch 162 and connect load R_(L1) 164 to the ports 158, 160 through the current sensing resistor R_(s1) 166. The POE IC 152 then measures the voltage on the sensing resistor R_(s1) 166 and the voltage V_(in1) at the nodes 168, 170, where V_(in1)=V⁺−V⁻. Note that the nodes 168, 170 correspond to the ports 158, 160. Since the resistance of sensing resistor R_(s1) 166 is known, the current I₁ can be calculated by the ratio between the voltage measured on the resistor to the resistance of the resistor. Based on this truth, the following equation can be formulated.

V _(in1) =V _(out) −I ₁ *R _(LINE)   (1)

With continued reference to FIG. 5, the controller 150 then instructs the POE IC 152 to open switch 162 and close switch 172, which connects load R_(L2) 174 to the ports 158, 160 through the current sensing resistor R_(s2) 176. The POE IC 152 then measures the voltage on the sensing resistor R_(s2) 176 and the voltage V_(in2) at the nodes 168, 170, where V_(in2)=V⁺−V⁻. Since the resistance of sensing resistor R_(s2) 176 is known, the current 1 ₂ can be calculated by the ratio between the voltage measured on the resistor to the resistance of the resistor. Based on this truth, the following equation can be formulated.

V _(in2) =V _(out) −I ₂ *R _(LINE)   (2)

By simultaneous solution of Eq. 1 and Eq. 2, V_(out) and R_(LINE) can be found. Then the available power at the ports 158, 160 can be calculated for any given current consumption I by solving:

P _(in) =−I ² *R _(LINE)   (3)

When the process is finished, both switches 162, 172 are opened and switch 156 may be closed for normal operation. If the power P_(in) is not sufficient for the operating of the “real” load 154, the RU 102 may disconnect some lower priority services within the “real” load 154. In an exemplary embodiment, R_(L1) 164 and R_(L2) 174 are 4.7 kΩ and 680 Ω respectively. Note that these values are exemplary and may vary as needed or desired, although in general, a resistance of at least 650 Ω is required coupled with enough spacing between the values for resistors 164, 174 for a meaningful measurement to be made. Thus, the exemplary values for these resistances may vary by about 10%. These values for the resistors 164, 174 are chosen to allow the power dissipated during the current and voltage measurements to meet the pulse power rating of the power resistors 164, 174 and not be physically too large within the device. In an exemplary embodiment, the resistors are the PWC2010-4K7JI and the PWC2010-680RI sold by TT Electronics of Clive House, 12-18 Queens Road, Weybridge, Surrey, KT13 9XB, England.

While the above explanation sets forth the process through which the available power may be calculated, FIG. 6 provides a flow chart of the process 180 more explicitly. The process 180 begins when the “real” load 154 having services and functions and POE IC 152 are installed in the RU 102 (block 182). Note that installation of such services may be a new installation of a new RU 102 or an additional service being added to an existing and previously deployed RU 102. In an exemplary embodiment, power will have been disconnected from the RU 102 or not yet have been attached. Accordingly, the power is connected to the RU 102 (block 184).

With continued reference to FIG. 6, the controller 150 opens the switch 156 and closes (through the POE IC 152) switch 162 (block 186). Stated another way, the controller 150 deactivates all services and functions of the RU 102 (except the power sensing process herein described) by opening the switch 162. The controller 150 then measures, using the POE IC 152, the current I₁ and the voltage V_(in1) (block 188). The controller 150 then opens switch 162 and closes switch 172 (block 190). The controller 150 measures, through POE IC 152, the current I₂ and the voltage V_(in2) (block 192). From the two measurements, the controller 150 may calculate the maximum power available P_(in) at the RU 102 (block 194). The calculation is a function of two equations with two unknowns and becomes a routine solution as shown above.

With continued reference to FIG. 6, the controller 150 can compare available P_(in) to the expected power demands of the “real” load 154 (block 196). If the answer to the comparison is positive, that there is enough power, then the RU 102 may operate normally (block 198). If, however, the answer is negative, that the power required by the “real” load 154 exceeds P_(in), then the controller 150 may take remedial action (block 200).

In exemplary embodiments, remedial actions include reducing transmission power of one or more of the services or functions within the “real” load 154, shutting off completely one or more of the services or functions within the “real” load 154, or generating an alarm. As noted above, the calculated R_(LINE) may also be reported and saved for future planning purposes.

In an alternate embodiment, the power supply output voltage V_(OUT) may be known (from direct measurement, prior calculations, or the like) in which case only a single equation is needed to solve for the unknown variable R_(LINE). Having to solve for only one variable means that only one equation is needed.

FIG. 7 is a schematic diagram representation of additional detail regarding an exemplary computer system 400 that may be included in the power distribution module 130 or the RU 102. The computer system 400 is adapted to execute instructions from an exemplary computer-readable medium to perform power management functions. In this regard, the computer system 400 may include a set of instructions for causing the controller 150 to enable and disable the services or functions within the “real” load 154, as previously described. The RU 102 or power distribution module 130 may be connected (e.g., networked) to other machines in a LAN, an intranet, an extranet, or the Internet. The RU 102 or power distribution module 130 may operate in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. While only a single device is illustrated, the term “device” shall also be taken to include any collection of devices that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. The controller 150 may be a circuit or circuits included in an electronic board card, such as a printed circuit board (PCB) as an example, a server, a personal computer, a desktop computer, a laptop computer, a personal digital assistant (PDA), a computing pad, a mobile device, or any other device, and may represent, for example, a server or a user's computer.

The exemplary computer system 400 in this embodiment includes a processing device or processor 402, a main memory 414 (e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM), etc.), and a static memory 406 (e.g., flash memory, static random access memory (SRAM), etc.), which may communicate with each other via the data bus 408. Alternatively, the processing device 402 may be connected to the main memory 414 and/or static memory 406 directly or via some other connectivity means. The processing device 402 may be a controller, and the main memory 414 or static memory 406 may be any type of memory.

The processing device 402 represents one or more general-purpose processing devices such as a microprocessor, central processing unit, or the like. More particularly, the processing device 402 may be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a processor implementing other instruction sets, or processors implementing a combination of instruction sets. The processing device 402 is configured to execute processing logic in instructions 404 for performing the operations and steps discussed herein.

The computer system 400 may further include a network interface device 410. The computer system 400 also may or may not include an input 412 to receive input and selections to be communicated to the computer system 400 when executing instructions. The computer system 400 also may or may not include an output 422, including but not limited to a display, a video display unit (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)), an alphanumeric input device (e.g., a keyboard), and/or a cursor control device (e.g., a mouse).

The computer system 400 may or may not include a data storage device that includes instructions 416 stored in a computer-readable medium 418. The instructions 424 may also reside, completely or at least partially, within the main memory 414 and/or within the processing device 402 during execution thereof by the computer system 400, the main memory 414 and the processing device 402 also constituting computer-readable medium 418. The instructions 416, 424 may further be transmitted or received over a network 420 via the network interface device 410.

Many modifications and other embodiments of the embodiments set forth herein will come to mind to one skilled in the art to which the embodiments pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. For example, the distributed antenna systems could include any type or number of communications mediums, including but not limited to electrical conductors, optical fiber, and air (i.e., wireless transmission). The distributed antenna systems may distribute any type of communications signals, including but not limited to RF communications signals and digital data communications signals, examples of which are described in previously incorporated U.S. patent application Ser. No. 12/892,424.

Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred.

It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the invention. Since modifications combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and their equivalents. 

What is claimed is:
 1. A remote unit for use in a distributed communication system, comprising: at least one antenna configured to transmit radio frequency signals into a coverage area; a power input configured to receive a power signal from a power distribution module through a power medium; a power over Ethernet integrated circuit (POE IC) configured to measure voltage and current from the power input; and a control system configured to: open a services switch between the power input and a real load; instruct the POE IC to close a first switch coupling a first load resistance to the power input; instruct the POE IC to measure a first voltage and a first current associated with the first load resistance; instruct the POE IC to open the first switch and close a second switch coupling a second load resistance to the power input; instruct the POE IC to measure a second voltage and a second current associated with the second load resistance; and calculate an available power for the remote unit.
 2. The remote unit of claim 1, further comprising the services switch, the first switch and the second switch.
 3. The remote unit of claim 1, wherein the POE IC comprises a current sensor.
 4. The remote unit of claim 1, wherein the POE IC comprises a voltage sensor.
 5. The remote unit of claim 1, wherein the remote unit is configured to receive communication signals from a fiber infrastructure.
 6. The remote unit of claim 1, wherein the control system is configured to generate an alert if available power is insufficient for all services at the remote unit.
 7. The remote unit of claim 1, wherein the control system is further configured to shut off a service if power is insufficient for all services.
 8. The remote unit of claim 1, wherein the control system is further configured to reduce transmission power for one or more services if power is insufficient for all services.
 9. The remote unit of claim 1, wherein: the POE IC comprises at least one of a current sensor and a voltage sensor; the control system is configured to reduce transmission power for one or more services if power is insufficient for all services; and the remote unit comprises a plurality of service modules configured to provide the services at the remote unit, the plurality of service modules comprising service modules selected from the group consisting of: cellular service, radio frequency communications, WiFi, Ethernet, and location based services.
 10. The remote unit of claim 1, further comprising a plurality of service modules configured to provide the services at the remote unit.
 11. The remote unit of claim 10, wherein the plurality of service modules comprises service modules selected from the group consisting of: cellular service, radio frequency communications, WiFi, Ethernet, and location based services.
 12. The remote unit of claim 1, wherein the first load resistance comprises approximately 680 Ω and the second load resistance comprises approximately 4.7 kΩ.
 13. A method of managing power in a remote unit of a distributed communication system, the method comprising: opening a services switch associated with a real load; while a first switch associated with a first resistance is closed, measuring a first voltage and first current associated with the first resistance; while a second switch associated with a second resistance is closed, measuring a second voltage and a second current associated with the second resistance; and calculating an available power for the remote unit based on the first current, the first voltage, the second current and the second voltage.
 14. The method of claim 13, further comprising closing the first switch after opening the services switch.
 15. The method of claim 13, further comprising opening the first switch after measuring the first voltage and the first current.
 16. The method of claim 13, further comprising closing the second switch after opening the services switch.
 17. The method of claim 13, further comprising opening the second switch after measuring the second voltage and the second current.
 18. The method of claim 17, further comprising closing the services switch after opening the second switch.
 19. The method of claim 13, wherein measuring comprises measuring with sensors within a power over Ethernet integrated circuit (POE IC).
 20. A distributed communication system, comprising a plurality of remote units, each remote unit comprising: at least one antenna configured to transmit radio frequency signals into a coverage area; a power input configured to receive a power signal from a power distribution module through a power medium; a power over Ethernet integrated circuit (POE IC) configured to measure voltage and current from the power input; and a control system configured to: open a services switch between the power input and a real load; instruct the POE IC to close a first switch coupling a first load resistance to the power input; instruct the POE IC to measure a first voltage and a first current associated with the first load resistance; instruct the POE IC to open the first switch and close a second switch coupling a second load resistance to the power input; instruct the POE IC to measure a second voltage and a second current associated with the second load resistance; and calculate an available power for the remote unit. 